It looks like a literal token. Programming Perl v.3 says, "You should consider any identifier that both begins and ends with a double underscore to be reserved for special syntactic use by Perl." (page 68)

When I put that line in a seperate script I get the error:
"Undefined subroutine &main::__VALUE__ called ..."

There is other whackiness in this script, things like __TAG__ and __INSERT__

BTW - This is all going on inside a Perl script written for Interwoven. They seem to be subroutines, but why would anybody use literal tokens for subroutine names?. Is it even possible for people to add custom literal tokens to Perl?